1. Field of Invention
The invention relates to a method for the air-free filling of the blood side of a hemodialysis apparatus with liquid such as a physiological electrolyte solution and for the venting of the blood side of a hemodialysis apparatus during operation.
2. Description of the Prior Art
It is already known to provide air separators formed as chambers for the separation of air in extracorporeal blood circuits in blood removing line systems, that is in the so-called venous part of the extracorporeal blood circuit. An air cushion is usually formed over a liquid level during use in these air separators since there is permanent air communication between the inside of the chamber and the environment. There are also discussions whether such a blood/air contact should be avoided for blood compatibility reasons. An air separator has therefore already been proposed in U.S. Pat. No. 5,849,065 A which is completely filled with blood. Such an air separator, however, has the disadvantage that a hydrophobic membrane which should prevent the discharge of blood is itself constantly in contact with the blood. This can now result in clogging of the membrane and furthermore the blood itself is still in contact with the air via the membrane surface since the membrane actually has a porosity of approx. 60% and thus only represents a visual air barrier. In the embodiments used, especially coated air separator membranes are used which have been developed for blood systems. These especially developed membranes are comparatively expensive. On damage to the membrane, a comparatively high safety risk results since blood can exit here, on the one hand, and since there is a risk of cross-contamination, on the other hand.
The filling of the extracorporeal blood circuit of dialysis machines is described by way of example in EP 0 560 368 A2 as well as in DE-1 00 11 208 C1.
The subsequent separation of air from a system is known from US 2003/0,135,152 A. US 2002/0017489 explains the use of a deposition line having a clamp and a check valve.
It is already known from EP 0 161 686 B1 to provide a valve and to arrange a conventional hydrophobic membrane after the valve.